1. Field of the Invention
This invention relates to the synthesis of quaternized, dye-complexable vinylpyridine carboxylate mono-, co- and ter- polymers in high yield and purity, employing suspension polymerization and subsequent quaternization of the resulting vinyl pyridine polymer.
2. Description of the Prior Art
Dye completing polymers have been used in laundry detergent and fabric softener compositions to stabilize and minimize leaching of dyes in colored fabrics. During washing of colored and white fabrics, some of the dyes can bleed out of a colored fabric and a portion of the leached dye may deposit on white or lighter colored fabrics. The degree of bleeding is influenced by the character of the dye, the type of cloth and the pH, temperature and mechanical efficiency of the agitation process. Although in some cases the bled dye in the wash liquor can be washed off without altering the color of lighter colored fabrics, the dyed fabric looses a degree of brilliance resulting in a somewhat faded appearance. Often it is found that the fugitive dye deposits either onto the same fabric or onto another fabric leading to patches and streaks in the washed material. This deposition of the bled dye can be inhibited in several ways. One method involves the use of a dye transfer inhibitor (DTI) compound which can complex with the dye and minimize leaching or at least prevent redeposition on the same or other fabrics.
Polyvinylpyrrolidone (PVP), by virtue of its dye complexation ability, has been used to inhibit dye deposition during washing of colored fabrics under laundry conditions. The performance of PVP as a DTI, however, is adversely affected by the presence of anionic surfactants usually present in the washing process.
Vinylpyridine polymers such as those disclosed in U.S. Pat. No. 4,824,910 and in our previous U.S. Pat. Nos. 5,776,879 and 5,929,175, were formerly synthesized in alcoholic media; however, the product of this process contains significantly high unreacted monomer for a given period of reaction time and requires separation of organic solvent to recover pure polymer product. Costly and time consuming treatments are employed to remove impurities with the organic solvent in order to recover a purified product having no objectionable color.
Emulsion polymerization of vinylpyridine prior to quaternization has also been considered; however, this system requires the presence of a surfactant which is objectionable in certain formulations. For example, in cosmetic or pharmaceutical formulations which require specialized wetting agents for the active component, interactions with any remaining amount of surfactant in the polymer product can lead to an undesirable side reaction and/or a discoloration of the formulation. Also, certain dyes are sensitive to and interact with surfactants; thus their presence can cause problems in laundering compositions particularly when used in hot washing and rinsing cycles.
Accordingly, it is an object of this invention to provide a process for the preparation of water stable, quaternized, complexable vinyl pyridine carboxylate polymers which are not subject to the above objections and disadvantages.
Another object is to provide an economical and commercially feasible process for the preparation of a water soluble dye transfer inhibitor and stabilizing component for agrochemical, cosmetic or pharmaceutical formulations which are obtained in high purity suitable for immediate use.
A further feature of the invention is a process for providing a water soluble vinylpyridine polymer containing a quaternary nitrogen and a carboxylate salt in high yield and purity which is free of surfactant.
Another object of the invention is to provide a laundry detergent composition which effectively resists fabric dye transfer or discoloration during the washing and rinsing cycles.
These and many other benefits and advantages of this invention will become apparent from the following description and disclosure.